From bebd51479ebc5f2cdd25b872f80db03b048b8937 Mon Sep 17 00:00:00 2001
From: Nipun Garg
Date: Wed, 3 Jul 2019 07:06:35 +0530
Subject: HDB: Add traceStraightPath()

---
 engines/hdb/ai-waypoint.cpp | 134 ++++++++++++++++++++++++++++++++++++++++++++
 engines/hdb/ai.h            |   1 +
 2 files changed, 135 insertions(+)

(limited to 'engines')

diff --git a/engines/hdb/ai-waypoint.cpp b/engines/hdb/ai-waypoint.cpp
index 70847aba8b..c930a0c1a0 100644
--- a/engines/hdb/ai-waypoint.cpp
+++ b/engines/hdb/ai-waypoint.cpp
@@ -71,6 +71,140 @@ void AI::clearWaypoints() {
 	_numWaypoints = 0;
 }
 
+bool AI::traceStraightPath(int x1, int y1, int *x2, int *y2, int *level) {
+	int	xVel, yVel, ok, entOK;
+	AIEntity *e;
+
+	// this checks to make sure we're only going vert or horz
+	if (x1 != *x2 && y1 != *y2)
+		return false;
+
+	// this sets a -1, 0, or 1 step value
+	xVel = *x2 - x1;
+	if (xVel < 0)
+		xVel = -1;
+	if (xVel > 0)
+		xVel = 1;
+
+	yVel = *y2 - y1;
+	if (yVel < 0)
+		yVel = -1;
+	if (yVel > 0)
+		yVel = 1;
+
+	while (1) {
+		// clear tile ahead?
+		entOK = ok = 0;
+		uint32 flags = g_hdb->_map->getMapBGTileFlags(x1, y1);
+		if (flags & kFlagStairTop)
+			*level = 2;
+		else if (flags & kFlagStairBot)
+			*level = 1;
+
+		// Floor level 1
+		if (*level < 2) {
+			ok = !(flags & (kFlagPlayerBlock | kFlagMonsterBlock));
+			// if it's blocking, is it rad or plasma? (might be melted stuff on it)
+			if (!ok) {
+				ok = ((flags & kFlagPlasmaFloor) == kFlagPlasmaFloor) +
+					((flags & kFlagPlasmaFloor) == kFlagRadFloor);
+				e = findEntity(x1, y1);
+				if (e && g_hdb->_ai->walkThroughEnt(e->type))
+					entOK = 1;
+				else if (ok && e && (e->state == STATE_FLOATING || e->state == STATE_MELTED || e == _player))
+					entOK = ok = 1;
+				else
+					ok = 0;
+			} else if (ok &&
+				((flags & kFlagWater) == kFlagWater ||
+				(flags & kFlagSlime) == kFlagSlime)) {
+				// if it's non-blocking, is there water or slime?
+				e = findEntity(x1, y1);
+				if (e && g_hdb->_ai->walkThroughEnt(e->type))
+					entOK = 1;
+				else
+					if (e && (e->state == STATE_FLOATING || e->state == STATE_MELTED || e == _player))
+						entOK = ok = 1;
+					else
+						ok = 0;
+				}
+		} else {
+			// Floor level 2
+			if (g_hdb->_map->getMapFGTileIndex(x1, y1) >= 0)			// is there a foregnd tile? its flags take precedence on Level 2
+				ok = !(g_hdb->_map->getMapFGTileFlags(x1, y1) & (kFlagPlayerBlock | kFlagMonsterBlock));
+			else {
+				flags = g_hdb->_map->getMapBGTileFlags(x1, y1);
+				ok = !(flags & (kFlagPlayerBlock | kFlagMonsterBlock));
+				// if it's blocking, is it rad or plasma? (might be melted stuff on it)
+				if (!ok) {
+					ok = ((flags & kFlagPlasmaFloor) == kFlagPlasmaFloor) +
+						((flags & kFlagPlasmaFloor) == kFlagRadFloor);
+					e = findEntity(x1, y1);
+					if (e && g_hdb->_ai->walkThroughEnt(e->type))
+						entOK = 1;
+					else if (ok && e && (e->state == STATE_FLOATING || e->state == STATE_MELTED || e == _player))
+							entOK = ok = 1;
+					else
+						ok = 0;
+				} else if (ok &&
+					((flags & kFlagWater) == kFlagWater ||
+					(flags & kFlagSlime) == kFlagSlime)) {
+					// if it's non-blocking, is there water or slime?
+					e = findEntity(x1, y1);
+					if (e && g_hdb->_ai->walkThroughEnt(e->type))
+						entOK = 1;
+					else
+						if (e && (e->state == STATE_FLOATING || e->state == STATE_MELTED || e == _player))
+							entOK = ok = 1;
+						else
+							ok = 0;
+				}
+			}
+		}
+
+		if (ok) {
+			e = findEntity(x1, y1);
+			if (e == _player)
+				e = NULL;
+			else if (g_hdb->_map->laserBeamExist(x1, y1)) {
+				*x2 = x1 - xVel;
+				*y2 = y1 - yVel;
+				return true;
+			} else if (e && (e->level != _player->level) && (g_hdb->_map->getMapFGTileFlags(e->tileX, e->tileY) & kFlagGrating)) {
+				// on the same level????
+				entOK = 1;
+			}
+
+			if (e && !entOK) {
+				if (g_hdb->_ai->walkThroughEnt(e->type)) {
+					// yes! are we at desired location?
+					if (x1 == *x2 && y1 == *y2)
+						return true;
+				} else {
+					// solid tile! back up one and return!
+					*x2 = x1 - xVel;
+					*y2 = y1 - yVel;
+					return true;
+				}
+			} else if (x1 == *x2 && y1 == *y2) {
+				// yes! are we at desired location?
+				return true;
+			}
+		} else	{
+			// solid tile! back up one and return!
+			*x2 = x1 - xVel;
+			*y2 = y1 - yVel;
+
+			return true;
+		}
+
+		x1 += xVel;
+		y1 += yVel;
+	}
+
+	return true;
+}
+
 Tile *AI::getStandFrameDir(AIEntity *e) {
 	switch (e->dir) {
 	case DIR_DOWN:
diff --git a/engines/hdb/ai.h b/engines/hdb/ai.h
index 1ab2b86bb9..80f7a71221 100644
--- a/engines/hdb/ai.h
+++ b/engines/hdb/ai.h
@@ -946,6 +946,7 @@ public:
 	void addWaypoint(int px, int py, int x, int y, int level);
 	void removeFirstWaypoint();
 	void clearWaypoints();
+	bool traceStraightPath(int x1, int y1, int *x2, int *y2, int *lvl);
 	Tile *getStandFrameDir(AIEntity *e);
 	void drawWayPoints();
 	int waypointsLeft() {
-- 
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